9 results about "Ultrasonic lamb waves" patented technology

The invention discloses an aluminum plate ultrasonic Lamb wave denoising method based on ICPO-VMD combined improvement of a wavelet threshold, and the method comprises the steps: collecting an ultrasonic echo signal of an aluminum plate, carrying out the adaptive optimization through an improved crown porcupine optimization algorithm, and obtaining an optimal parameter combination; performing variational mode decomposition on the ultrasonic echo signal by using the optimal parameter combination to obtain a plurality of intrinsic mode function components; calculating a correlation coefficient of each intrinsic mode function component and the original ultrasonic echo signal, and dividing all the components into a signal dominant component, a mixed component and a noise dominant component according to a preset correlation coefficient threshold; de-noising processing is carried out on the mixed component by adopting an improved wavelet threshold function; and reconstructing the signal dominant component and the denoised mixed component to obtain a denoised Lamb wave signal. According to the invention, high-fidelity and high-reliability de-noising processing of the ultrasonic Lamb wave signal of the aluminum plate is realized, and the accuracy and robustness of subsequent defect detection are improved.

The application relates to an acoustic metamaterial with a frequency-doubling filtering characteristic and a shape optimization method thereof, the optimization method comprising the following steps: constructing a two-dimensional finite element simulation model, the two-dimensional finite element simulation model comprising a main plate, a thin adhesive layer and an acoustic metamaterial, the acoustic metamaterial having an initial structure, the initial structure being periodically arranged by an initial unit cell structure, and a free-shape boundary being arranged in the initial structure; constructing an optimization model according to a target that a fundamental frequency is a passband and a frequency double is a stopband; adjusting the free-shape boundary on the basis of the initial structure by using a moving asymptote method; and calculating to obtain an optimal structure of the acoustic metamaterial. Compared with the prior art, the application not only ensures that the optimization target can be achieved, but also reduces the complexity of the structure, facilitates processing and manufacturing, and the designed acoustic metamaterial has the frequency-doubling filtering characteristic, and can effectively filter the inevitable system nonlinearity in nonlinear ultrasonic Lamb wave detection.

This invention discloses a method for inverting the velocity of the cemented medium behind the casing based on ultrasonic Lamb waves, relating to the field of geophysical logging. This invention utilizes a back-casing scanning imaging logging instrument to perform ultrasonic Lamb wave logging and ultrasonic pulse reflection logging at various depth points, acquiring waveform records at each depth point. The casing thickness and acoustic impedance of the cemented medium behind the casing at specified azimuths are inverted and calculated. Based on the ultrasonic Lamb wave logging waveform records, Fourier transforms are performed on the near-curved and far-curved Lamb wave full-wave waveforms at each specified azimuth of each depth point, calculating the phase difference between near and far-curved Lamb waves and performing group delay processing. Combining this with the operating frequency band of the back-casing scanning imaging logging instrument, the frequency values ​​corresponding to the minimum values ​​of the group delay at each azimuth of each depth point are obtained. After obtaining the frequency set, the wave velocity and medium type of the cemented medium behind the casing are determined based on the frequency values, the number of minimum frequencies, and the acoustic impedance values ​​at each azimuth of the frequency set.

The application discloses a large-interval array ultrasonic signal anti-symmetry Lamb wave dispersion extraction method for a cased well, an electronic device and a program product. The method comprises the following steps: constructing a Hankel matrix according to a frequency domain space sequence of a large-interval ultrasonic Lamb wave array signal, and then solving spatial poles; constructing a Vandermonde matrix according to the spatial poles, and then solving real complex amplitudes of the spatial poles; performing adaptive dynamic phase unwrapping on the spatial poles according to a phase velocity of a prior A0 mode, and obtaining phase velocities and spatial attenuation coefficients of all spatial poles in a full frequency band; selecting an initial anchor point according to the real complex amplitudes of the poles in a dynamic pole library; eliminating cross modes and noise interference according to the initial anchor point and a monotonicity constraint of the phase velocity; eliminating artifact points according to a difference between an error mean of imaginary parts of the dynamic poles and a fitting curve and a fitting variance, and obtaining a final A0 mode dispersion curve. The application effectively suppresses spatial aliasing and mode cross artifact.

The invention discloses an air coupling Lamb wave detection device and method for a ceramic matrix composite component, and belongs to the technical field of ultrasonic nondestructive detection. Comprising a control system, a six-degree-of-freedom industrial robot, a detection system arranged at the tail end of the six-degree-of-freedom industrial robot, and a ceramic matrix composite spraying pipe arranged at the end, away from the six-degree-of-freedom industrial robot, of the detection system. The spray pipe clamping mechanism is arranged below the ceramic matrix composite spray pipe; the spray pipe rotating mechanism is arranged below the spray pipe clamping mechanism; through mutual cooperation of all the parts, an air coupling ultrasonic lamb wave detection method and an automatic detection system are applied, and automatic detection of internal defects of the ceramic matrix composite spraying pipe of the airspace engine is achieved. According to the air coupling Lamb wave detection device and method for the ceramic-based composite component, nondestructive evaluation is carried out on the internal quality of the ceramic-based composite spray pipe, and the device and method have important significance on development of the spaceflight cause.

The invention relates to the technical field of fatigue crack nondestructive testing, in particular to an orthotropic steel bridge deck fatigue crack Lamb wave signal fusion processing method which comprises the steps that theoretical analysis and numerical simulation are conducted on an orthotropic steel bridge deck ultrasonic Lamb wave signal, and Lamb wave detection basic parameters are obtained; based on Lamb wave detection basic parameters and original signals, baseline correction is carried out on the Lamb wave signals, signal baseline drift caused by the load effect is eliminated, and to-be-separated signals without baseline interference are obtained; for a to-be-separated signal without baseline interference, performing multi-mode separation on the Lamb wave signal after baseline correction, extracting a low-order symmetric vibration mode signal and a low-order anti-symmetric vibration mode signal of the Lamb wave, and obtaining a single-mode original signal; and processing the separated single-mode signal, and correcting the frequency dispersion compensation process by combining with the thickness change caused by the fatigue crack damage of the orthotropic steel bridge deck to obtain a single-mode non-frequency dispersion signal. And a high-quality detection signal can still be obtained in a non-ideal environment.

This invention discloses a cement velocity inversion method based on arrayed ultrasonic Lamb waves, belonging to the field of oil and gas well exploration and development technology. It solves the technical problems of low computational efficiency and limited applicable velocity range in cement velocity inversion algorithms. The method includes: performing spatiotemporal preprocessing on the array signal to obtain the target guided wave mode, and extracting the complex dispersion curve of the target guided wave mode; constructing a three-layer planar medium model and deriving the dispersion matrix; setting the acoustic parameters of the well fluid and casing, generating multiple sets of initial value sequences for the parameters to be inverted, and calculating the determinant of the dispersion matrix; constructing a loss function, iteratively updating the parameters to be inverted and repeating the process until the number of iterations reaches a preset iteration threshold; traversing all sets of initial value sequences and extracting the iteration parameters corresponding to the round in which the loss function reaches its minimum value. This invention broadens the applicable working conditions and universality, facilitates automated and batch processing, and improves computational efficiency.

The present application relates to a kind of sound-absorbing metamaterials for near boundary damage ultrasonic imaging detection and design method and ultrasonic imaging detection method, sound-absorbing metamaterials are made of at least 1 sound-absorbing metamaterial unit, design method includes: according to ultrasonic detection frequency, the geometric parameter range and material parameter range of sound-absorbing metamaterial unit are determined;Establish near boundary defect ultrasonic lamb wave detection finite element model, the reflection phase and reflectivity of sound-absorbing metamaterial unit under different geometric parameters and material parameters are calculated;According to multiple scattering theory, the number of sound-absorbing metamaterial unit is determined, so that the diffraction propagation mode of sound-absorbing metamaterial only exists 0 order diffraction propagation mode;The optimal geometric parameter and material parameter of sound-absorbing metamaterial unit are determined.Compared with prior art, the present application has the advantages of reducing the influence of high-energy boundary reflected wave on imaging result, improving the sensitivity and imaging accuracy of near boundary defect ultrasonic lamb wave detection and the like.

The invention discloses a laser ultrasonic Lamb wave signal noise reduction method for metal aluminum sheet defect detection. Comprising the following steps: collecting a Lamb wave signal to be measured, carrying out decomposition processing on the Lamb wave signal by adopting complete adaptive noise ensemble empirical mode decomposition (CEEMDAN), and solving the modal aliasing problem of a multi-order intrinsic mode (I MF) component by utilizing a Pearson coefficient method to obtain an I MF component without modal aliasing; calculating a permutation entropy value of each order of component, setting a threshold value, screening effective signal components, and performing primary reconstruction; performing stationary wavelet (SWT) decomposition processing on the primary reconstruction signal to obtain a low-frequency approximation coefficient and a high-frequency detail coefficient; constraining the high-frequency detail coefficient through an L2 regularization method; and carrying out secondary reconstruction on the reserved approximation coefficient and the detail coefficient after L2 constraint to obtain a Lamb wave signal after final noise reduction. The signal quality of the Lamb wave signal is improved, and the accuracy of defect detection of the metal aluminum sheet is improved.